Rotary tenter drier



Aug. 12, 1941. J. D. HUNTER ETAL ROTARY TENTER DRIER Filed Jan.' 12, 1938 4 Sheets-Sheet 1 EVE Aug.-12, 1941, J. D. HUNTER ETAL 2,252,181.

ROTARY TENTER DRIER Filed Jan. 12, .1938 4 Sheets-Sheet 2 Aug. 12 1941. HUNTER ET AL 2,252,181

ROTARY TENTER DRIER 2M QM, g m/ W 12, 1941- J. D. Hum-ER ETA L 2,252,181

ROTARY TENTER DRIER Filed Jan. 12, 1938 4 Sheets-Sheet 4 QW-M M,

Maw WK/QM M,

Patented Aug. 12, 1941 lTED srrss 2,252,1 1 rrics ROTARY TENTER DRIER Application'January 12, 1938, Serial No. 184,606

4 Claims.

This invention relates to tenter driers for stretching and drying te'xtile fabrics while traveling in extensive or continuous lengths, and as its object the provision of a tenter drier which shall be extremely rapid in its drying and hence i capable of a high rate of production, without having to use high temperatures, and which shall be of relatively small side and hence economical of floor space. It further aims to economize both on first cost and on upkeep, and to save on the power needed to propel the cloth through the machine. Another aim is to attain absolutely uniform drying across the entire width of the fabric, and to do so without stretching the cloth unevenly and pulling it out of shape, or producing bowed filling or slack selvages. Still another aim is to avoid the need for extensive greasing or lubricating of the tenter chains and their tracks, so asto diminish the risk of oil or grease getting on the cloth. An additional aim is to provide a drier which can easily be enlarged to increase its capacity or rate of production in case such change beeoines desirable. I

To these ends, the invention consists in the method of and means for stretching the traveling fabric widthwise while forcing copious quantities of air through the fabric, and supporting the fabric against distortion by the air blast throughout substantially the entire area that is thus subjected to the blast. For compactness and continuous operation, this is effected by running the fabric onto opposed tenter chains which run in a circular path around the rims of large rotating wheels joined by a cylindrical cage or screenof the same diameter, while heated air is forced in large quantities radially inward through the cylindrically-disposed fabric and the screen, the latter supporting the cloth over the entire area of such circuit around the cylinder so as to prevent distortion of the fabric under the blast. For efficiency, the heated air thus passed through the fabric into the cylinder is exhausted from the interior thereof and recirculated repeatedly and continuously radially inward. through the fabric, a small portion being continuously wasted and additional make-up air correspondingly admitted into the housing which encloses this large drying cylinder. Because the fabric is thus supported against distortion, there is n'o limit to the volume of air that can be used; for this reasornand because the air penetrates right through the fabric, rapid drying can be had without resort to high temperatures, and a. relatively short exposure to the air blast eiiects complete drying. Hence the cloth needs to stay within the drier only a short time, and thus a relatively short length of fabric is within the machine at any one instant. This not only makes the drier small and compact, but means a great saving of machine time in handling successive lengths of material of different widths and requiring emptying of the machine before making the necessary adjustment of the span of the machine, as it takes little time to get the old piece of'material out of the machine or to get the new piece into and through the drier. Because the tenter chains are thus carried wholly on wheels or pulleys while within .the machine, instead of having to slide along stationary tracks, there is a saving of both the usual wear occurring between the chains and their tracks as a result of the inward pull of the cloth and the wear on the pivots joining successive links of the chains resulting from repeated changes of direction of travel of the chains within thehousing, in the case of most prior types of tenter drier's. Also, since the tracks thus move with the chains, there is a great saving in the amount of power needed to drive the chains and the fabric through the machine. Correspondingly, there is much less need for lubricating the chains, and no" need of greasing the tracks within the housing. The driving of the chains is greatly simplified, being applied to the chains at only one point, namely where they emerge from the housing. Expansion of the chains under heat within the housing raises no difiiculties, and a simple idler introduced into theidle run of the chain after leaving the housing takes care of all slack.

The iniproveddrier dries the fabric uniformly across the entire width of the machine, due to the large cross-sectional area and corresponding absence of frictional resistance to the movement of the air transversely of the material both within and without the cylinder. As a result, the pressure or suction is uniform throughout the entire length of the cylinder, which means throughout the entire width of the fabric; and air is drawn through the cloth just as much at one selvage as at the other, or as at intermediate points in the width. In tenter driers which dispose the fabric in parallel runs air friction is always present to cause unequal drying, as the runs must be put relatively close to each other for economy of space and efiiciency, and the bellying of the unsupported material at midwidth under the air-pressure decidedly reduces the size of the air passages.

Through use of the screen supporting the fabric throughout the entire area thereof that is exposed to the blast, there can be no stretching of the central warps in the cloth or pulling of the wefts out of their intended straight extent from selvage to selvage, by the force of the air; thus plaids and checkedgoods and other fabrics bearing patterns are kept in undistorted relation.

If an increased rate of drying over that attainable through the use of the single cylinder described becomes necessary, it is easily possible to extend the rear end of the housing and the tenter chains to include one or more additional cylinders like the first one, running the fabric half way around the first and intermediate cylinders, then around nearly the entire circuit of the rearmost cylinder, and back around the other half of each of the aforesaid cylinders.

The circular path of the fabric within the housing makes it possible to dispose heating elements in close proximity to substantially the entire area of fabric that is within the housing without impeding the uniform drying by the airflow, so that the heat is applied to the fabric by direct radiation as well as by convection through the medium of heated air.

Other aims of the invention, and the manner of their attainment, are as will be made plain hereinafter.

An illustrative embodiment of the invention is shown in the accompanying drawings in which- Fig. 1 is a side elevation of the improved drier with one side-wall thereof removed.

Fig. 2 is a vertical transverse section partly on line 22 of Fig. 1, but with certain features lying in front of such section line also shown.

Fig. 3 is a side elevation similar to that shown in Fig. 1, illustrating the drive for the fan.

Fig. 4 is a vertical section through the feed and delivery rolls at the entrance to the housing, showing the adjustable damper used to control the make-up air.

Fig. 5 is a detail showing the means for positioning the movable side of the drying cylinder to suit the width of the fabric.

Fig. 6 is a diagram showing method of duplicating the cylinders to increase the capacity of the machine.

Fig. 7 is a detail view of the transfer shoe, in vertical section.

Fig. 8 shows an alternative form of the openwork-surfaced drum.

The drying drum or cylinder I has a foraminous cylindrical cloth-supporting surface, a closed air-impervious head 3 on one end, and an annular head 5 on the other end having a central aperture IUD through which air is exhausted by a coaxial fan I to induce the flow of air through the cloth 9 which is stretched by tenter chains II around the drum I. The foraminous cylindrical portion of the drum I comprises two telescoping cylindrical sections I3, I5, of metal screening, preferably expanded metal, though perforated metal or woven wire may be used. The inner end of section I3, which fits closely and accurately within the corresponding section I5, is reinforced by a ring I! welded or otherwise secured thereto and which is in turn attached to spokes I9 on hub 2| fixed on shaft 23 on which the drying cylinder I is mounted. The outward ends of screen sections I3 and I5 are similarly attached at their extremities to thin rings 25 attached by oblique strap 21 to spokes 29 radiating from hubs 3|, 33, of two large wheels or spiders, either of castiron or built-up. Hub 33 of the wheel nearest fan I is fixed on the shaft by set-screws, while hub 3| of the other wheel is splined to shaft 23 by feather 32 for movement in or out along such shaft to permit of the necessary telescoping of the two screen sections incident to adjustment for the width of the fabric. The tenter chains are carried on the flanged rims 35 on the ends of spokes 29 of the large wheels, and the heads 3, 5, of the drying drums are attached to the outward sides of the spokes 29.

The sliding hub 3| of the movable end of drum I has a positioning collar 31, Figs. 2 and 5, bolted to it, in the groove 39 of which fit the correspondingly-shaped edges of straps 4| of metal forming a yoke and fixed at top and bottom to channel irons 43 which in turn are fastened at each end at 45 to a pair of upright angle irons 41. These angle irons 4'! have attached to the inward face of their upper and lower extremities glands 49 containing nuts 5| engaging with jack screws 53 extending clear across the machine and journalled in bearings 55 in the uprights 51 of the machine frame. Each of the four jackscrews 53 has fixed thereon a sprocket 59 engaged with an endless chain GI, and an electric motor 63 mounted on a bracket on one upright 51 is connected by chain IE4 with sprocket 65 fixed on one of the screws to drive all four screws in unison to move the movable end of the drum in or out into properly spaced relation with the fixed end thereof to give the proper degree of widthwise stretch to the particular width of fabric being handled.

To save the expense of fitting the telescoping screens I3, I5 so accurately a to avoid the slight marking of one surface thereof by the inward end of larger section I5 of metal screening forming the drum, resulting from the cloth being pressed thereagainst by the air, the alternative drum construction of Fig. 8 may be employed. In this, the standing part of the drum is made as shown in Fig. 2 and described, except that screen section I3 is made longer axially than the widest fabric designed to be stretched in the machine, while the moving screen section I5 is replaced by a cylinder I4 of steel plate fitting closely to and telescoping over screen section I3 in analogous manner, having around the rim of its inward end a flange I6, the shiftable lefthand tenter chain II running on the surface of cylinder I4 and being held against flange I6 by the inward pull of the stretched cloth. Cylinder I4 i made long enough to be moved inward over screen section I3 to bring its inward extremity and thus the shiftable chain II as close to the other tenter chain as will be required for the narrowest fabric which will be stretched in the machine. Since the rest of the parts on and associated with this movable end of the drum are or may be as described hereinbefore, except where stated to be otherwise, and its end is closed as before by head 3, the ingress of air into drum I is wholly radial as before, and confined solely to the areas lying between the two chains, and thus the air must pass wholly through the fabric. Rollers I8 on brackets 20 at the ends of spokes I9 supporting the inner end of the now full length screen section I3 guide the inner end of chaincarrying cylinder I4 in spaced and concentric relation with screen section I3, to facilitate the telescoping movement during width adjustment of the machine. Construction of screen I3 out of a plurality of arcuate sections fastened together by inturned flanges 22 provides for the necessary stiffness of this prolonged section to resist deformation. Through the use of telescoping feed and delivery drums I3 of slightly greater diameter than the pitch diameter of their sprockets I I escape of the fabric from the tenter pins on the chains in passing around these sprockets is prevented. Adjustment of the movable end of the drum along shaft 23 by means of collar 31 is accomplished as related hereinbefore, except that an additional pair of angle irons 48 similar to 41 is provided, likewise having nuts at top and loottomvin screw threaded engagement with jack-screws 53, to carry the yokesII controlling the position of sprockets II, and also to carry the transfer-shoes 89, Fig. '7, because in this instance the shiftable chain trav els at the inner end instead of the outer end of cylinder I4 forming the movable end of the drum.

The main shaft 23, of the drum I is journalled in bearings 6! on horizontal channel-iron frame members 69 fixed half-way up the uprights 5! of the frame.

To wrap the fabric around practically the entire circuit of the foraminous surface of the drying drum I, the approaching and departing runs of the fabric are brought together at the entrance to the machine by running the tenter chains II around sprockets II fixed on the hubs of telescoping cylindrical metal feed and delivery rolls I3 fixed on shafts I5 journalled in uprights 51 as the front of the machine just above and below the level of shaft 23 of the drying cylinder. These rolls are of substantially the pitch diameter of their sprockets I I, preventing any sagging of the fabric in making the bend resulting from thus forcing the tenter chains toward each other and out of tangential relation to the periphery of drum I. Yokes II fixed oh angle irons M and engaging with collars I9 on the hubs of rolls I3 that are at the movable end of drum I compel such hubs to move inward or outward along their splined shafts I5 to stay in line with the flanges 35 on the main drum which form the chain tracks, as such drum is lengthened or shortened to suit the fabric.

The usual chain wings BI, adjustable widthwise by swivel-connected screw 82 to receive the unstretched material 9 and thereafter to carry the opposed chains in diverging paths to bring the fabric out to the width for which the drum I is set, are supported atone end by rollers 83 on a, ledge 85 on uprights BI of the frame. The wings are each pivoted on a pintle carried by a transfer shoe 89 which transfers the incoming runs of the chains to their respective sprockets II; the

shoe at the movable end of the drum is attached to the adjacent movable angle iron 41 so as always to be in line with the chain-guiding flange 35 on the movable end of drum I. The transfer shoes are supported by a fixed shaft SI mounted in supports 93 on the forward pair of uprights 51, the non-adjustable shoe at the fan end of cylinder I being fixed by clamp-screws in the pro-per place on shaft I to lay the chain on track 35 at that end.

The fabric 9 is applied as usual to the pins of the tenter chains I i at the narrow or right-hand end of wings 8|, Fig. 1 and is then carried into the housing of the dryer through a slot in the front panel I62 at 99, under the feed-roll I3, while the chains pass around sprockets II' at -pposite ends of such feed-roll, thence around practically the entire circuit of the main cylinder I, Where it iswholly supported by the foraminous surface of telescoping screens l3, I 5, and sub jected to thorough and uniform, permeation by heated air, which is compelled to pass through the fabric under the pressure of fan I which continuously and powerfully exhausts air from the single opening Iilll in the head of the cylinder positioned closely adjacent one side of fan I, and discharges it about the exterior of the cylinder. After having made nearly the entire circuit of drum I, the fabric and the tenter chains pass over the lower or delivery roll I3 and its associated sprockets II, the dried fabric diverging from and leaving the chains as it passes over the bottom edge of the slot 99 through being guided around bar or roller I62 and thence traveling to the usual piling or folding mechanism (not shown). Chains II thereafter pass around paired idler sprockets Hi4, I06, the latter rotating on fixed centers I08 and the former carried on studs IID at the end of swinging arms II2 pivoted on centers I08 and urged by plunger H4 and spring H6 in a direction to cause sprockets I84 to increase the sharpness of the bend they make in the chains, and thus to keep the chains yieldingly tight against their various supporting and guiding surfaces throughout their entire circuit. The usual brushes H8 are provided on swinging supports to push the fabric 9 onto the pins while supported by wings BI, a plurality of such brushes at each side of the machine being linked together by rods I29 so as to be applied and removed in unison.

The fan I is of centrifugal type, mounted on ball bearings to turn freely on one end of the slower-moving main shaft 23 on which the drying drum I is fixed". It is driven by a pulley I22 fixed on the end of its hub I24 which protrudes outside the heat-insulating panel I26 which are fitted in between the frame-members 51 to form the housing of the drier. An electric motor I23 on an elevated shelf 53E! on the housing drives the pulley andthe fan at high speed by means of belts I32. The fan has a solid disk of sheet metal I34 forming its outward side and attached to a bell I36 integral with hub I24; while its other side i a ring I38 having a central aperture matching the opening in the juxtaposed end 5 of drum I. The ring I38, or the annular portion of end 5 whichis overlapped by the vanes Ml together with disk EM, thus prevent escape of air displaced by the vanes in any direction except in a direction radially away from the fans axis, and permit only an axial inflow of air from the interior of the drum to replace that thus drawn out by centrifugal action.

Heat is supplied to expedite the drying by means of steam heaters I4 2, which are made in segmental and partly cylindrical form and dis posed in concentric relation to the drum and in close proximity to the foraminous surface thereof, so that they will both heat the cloth by direct radiation and so that the recirculated drying air which has to passradially inward through the fabric and the screen surface of the drum in order to complete its circuit will pass through the interstices of the heater to be warmed thereby. The curved heaters can be made, if desired, to encircle the entire circuit of drum I except that portion occupied by the feed and delivery rolls I3 and involved with the entry and exit of the fabric. The heaters have an axial length equal to the maximum length of drum I when fully extended, so that the widest fabric which can be dried in the machine will be uniformly exposed to heat across its entire width, to insure uniform drying. The construction of the heaters is sim ple, comprising segmental headers IM at each end, joined by pipes I46 bearing extended-surface fins I 38, two sections being joined at top and bottom by bolts I50 put through studs I52 which extend through ears I54 at the meeting ends of the headers, and the extremities of each pair thus joined being mounted by their lugs on tie-rods I55 fixed to the uprights 5! of the frame. Steam is supplied from any suitable source.

The exhaust of moist air and the introduction of dry make-up air are respectively accomplished through exhaust pipe I58 opening through the roof of the machine and equipped with damper I99, and the space 99 in the front panel I52 of the machin through which the chains and the fabric enter and leave the housing. The action of fan 1 causes a pressure exhaust through pipe I58 and a suction intake through the space 99 and the confronting surface of the screen cylinder that is not covered by fabric. To control the rate of such air change inside the housing, a damper I64 made as shown in Fig. 4 is mounted by friction clamps I66 on fixed shaft 9| midway between the feed and delivery rolls f3. One end of one of the two telescoping lengths which jointly form this damper I64 is attached to the transfer shoe 89 at the movable end of drum I, by means of a collar and yoke, while the other length is held against endwise movement, so that as the width-adjustment of the length of drum I is varied by jack-screws 53, the damper I64 will always extend across the entire span between the two chains. Thus, to vary the rate of entry of make-up air, it is only necessary to reach in between the entering and departing runs of the chains or the fabric and change the inclination of damper I64 to close more or less completely the space between the two rolls I3. Where closure means is also desired for the part or opening 99 which lies at the left of the movable wing 8| when less than the maximum-width capacity of drum I is employed, a coil of thin sheet metal, spring-steel or spring-bronze, wide enough and long enough to cover the unused portion of slot 99, is rotatably mounted just in side the housing at the left-hand end of the slot, and its free end is attached to the left-hand side of wing 8|, the sheet metal winding up or un- Winding as the wing is adjusted outwardly or inwardly so as to keep the unused part of th slot covered.

The drive of the chains, cylinders, and fabric is very simple, being accomplished solely through driving the tenter chains at a single point in the length of each chain, namely by means of the sprockets II at opposite ends of the delivery roll 13. This is done through a sprocket I66 fixed on shaft I5 of lower roll I3,'connected by chain I68 with a sprocket I'Ifl on the power take-off shaft of a variable speed drive I'IZ driven by motor I74. From one-half to one horse power is all that is required for motor I'I'4 in a drier of my novel type employing a drying drum 6 feet in diameter, as the entire chain is there only some 32 feet long, and travels on parts which move with it in good bearings and at relatively slow speed, except in traveling the length of the top run on the wings 8|.

Fig. 6 makes plain how simply the capacity of the machine can be increased to get more rapid production, by simply extending the housing at the back of the machine to make room for the installation of a second drying cylinder 2 and fan 8 identical in every respect with cylinder I and fan I; the tenter chains II are likewise extended and a pair of rolls 14 corresponding exactly in construction, location and operation to feed and delivery rolls I3 is installed immediately above and below the point of nearest ap proach of the two cylinders to each other. The remaining parts and functions of the drive are substantially as described hereinbefore.

While we have illustrated and described certain forms in which the invention may be embodied, we are aware that many modifications may be made therein by any person skilled in the art, without departing from the scope of the invention as expressed in the claims. Therefore, we do not wish to be limited to the particular forms shown, or to the details of construction thereof, but what we do claim is:

1. In a machine for stretching and drying continuous web material, in combination, a housing, fresh air inlets and moist air outlets therein, opposed endless tenter chains running into and out of such housing, driving means for the chains, a foraminous cylinder around which the chains carry the web material within the housing while stretching it widthwise and rotating the cylinder, and means heating and recirculating air already within the housing repeatedly through the web material in a direction radially inward of the cylinder.

2. In a machine for stretching and drying continuous web material, in combination, a housing, fresh air inlets and moist air outlets therein, 0pposed endless tenter chains running into and out of such housing, driving means for the chains, at least one cylinder having an air-pervious surface rotatably mounted within th housing, means in connection with the cylinder engaged by and supporting the chains throughout substantially the entire circuit of the periphery of the cylinder and rotated by the chains and in turn rotating the cylinder, air heating means, and means recirculating heated air already within the housing inwardly repeatedly through the periphery of the cylinder and through the web material stretched around such periphery by the tenter chains and supported by such periphery against the air-blast.

3. In a drying machine for continuous web material, in combination, a housing, a cylinder rotatably mounted therein having an air-pervious peripheral surface, opposed tenter chains rotating the cylinder and carrying th material around and in contact with such peripheral surface, means driving the chains, air heating means, means recirculating heated air radially inward through the surface of the cylinder and through the material supported by the cylinder, guide means for the chains bringing the points of arrival and departure of the chains into proximity with each other whereby the chains and the material borne thereby substantially encircle the cylinder, and means for preventing passage of the air through that portion of the peripheral surface of the cylinder left uncovered by the traveling material.

4. In a machine for stretching and drying continuous web material, in combination, a housing, air-heating means, opposed endless tenter chains carrying the web in widthwise-stretched relation, propelling means therefor, a first cylinder having an air-pervious surface, a second cylinder telescoping over the pervious cylinder, having an impervious surface and a closed end, means guiding one tenter chain around th open end of the second cylinder, and the other chain around that end of th first cylinder remote from the second cylinder, the chains rotating the cylinders in unison, and means exhausting air through the end of the pervious cylinder and applying it over the air-pervious surface thereof for recirculation through the air-pervious surface and the web stretched thereover.

JAMES D. HUNTER.

FRANK B. MORRILL. 

